Optical image stabilization synchronization of gyroscope and actuator drive circuit

ABSTRACT

Various embodiments provide an optical image stabilization circuit that synchronizes its gyroscope and drive circuit using gyroscope data ready signals and gyroscope reset signals. In response to a gyroscope data ready signal, the optical image stabilization circuit synchronously obtains position measurements of a camera lens when power drive signals are not transitioning from one power level to another power level, and synchronously transitions the power drive signals simultaneously with gyroscope reset signals. By synchronizing the gyroscope and the drive circuit, the gyroscope and other onboard sensing circuits are isolated from noise generated by the drive circuit.

TECHNICAL FIELD

The present disclosure is directed to synchronization of a gyroscope andan actuator drive circuit of an optical image stabilization circuit.

DESCRIPTION OF THE RELATED ART

Digital cameras have progressed to smaller sizes, lower weight, andhigher resolutions. A drawback to this development, however, has beenthe impact of minor movements on image quality. Particularly, subtlemovements or vibrations while capturing an image often causes imageblurring. This is especially a problem for smartphones with built-incameras, where users capture images with outstretched arms which have agreater chance of involuntary movements. Image stabilization is widelyused to minimize image blurring. Current methods of image stabilizationinclude digital image stabilization, electronics image stabilization,and optical image stabilization. Generally, digital image stabilizationand electronics image stabilization require large amounts of memory andprocessor resources. Optical image stabilization, on the other hand,minimizes memory and processor demands by adjusting the lens positionitself. As such, optical image stabilization is ideal for portabledevices, such as smartphones and tablets with built-in cameras.

In general, optical image stabilization minimizes image blurring bysensing movements of a housing and compensating for the movements byadjusting the position of the camera lens. For example, see “OpticalImage Stabilization (OIS),” Rosa et al, STMicroelectronics. Opticalimage stabilization circuits typically include a gyroscope, acontroller, and a drive circuit that includes a large current source todrive an actuator to move the camera lens.

Many optical image stabilization circuits are implemented usingintegrated solutions, such as a system in package or a tightlyintegrated printed circuit board, that have shared power and ground.Having shared power and grounds, however, causes optical imagestabilization circuits, particularly their sensing components, to besusceptible to power and ground noise. For example, the large currentsource of the drive circuit may produce vibrations and transients on thepower and ground when transitioning from one power level to anotherpower level. Such power and ground noise may adversely affect on-boardsensing components that are sensitive to power and ground noise, such asthe gyroscope. Ideally, any noise generated by the drive circuit shouldnot disturb the onboard sensing circuits of an optical imagestabilization circuit.

BRIEF SUMMARY

The present disclosure provides an optical image stabilization circuitthat synchronizes its gyroscope and drive circuit.

According to one embodiment, a housing includes a camera lens, anactuator to move the lens, a position sensor, and an optical imagestabilization circuit having a gyroscope, a drive circuit, and acontroller. The optical image stabilization circuit uses gyroscope dataready signals and gyroscope reset signals to synchronize the gyroscopeand the drive circuit. In response to a gyroscope data ready signal, theoptical image stabilization circuit synchronously obtains positionmeasurements of a camera lens when power drive signals are nottransitioning from one power level to another power level. Bysynchronizing the gyroscope sensing cycle, the position sensing timingand the power drive signal with each other, the gyroscope device andother onboard sensing circuits are isolated from noise generated by thedrive circuit. This ensures that accurate gyroscope and positionmeasurements are obtained.

The optical image stabilization circuit disclosed herein results inreliable and accurate measurements from the gyroscope and other onboardsensing circuits that are sensitive to noise.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing and other features and advantages of the presentdisclosure will be more readily appreciated as the same become betterunderstood from the following detailed description when taken inconjunction with the accompanying drawings.

FIG. 1A is a block diagram illustrating an example of a housingincluding an optical image stabilization circuit according to oneembodiment as disclosed herein.

FIG. 1B shows an example camera undergoing movement and correctionaccording to embodiments disclosed herein.

FIG. 2 is a flow diagram illustrating an example of a process for anoptical image stabilization circuit according to one embodiment asdisclosed herein.

FIG. 3 is a diagram illustrating a plurality of wave forms for aplurality of lens movement control cycles of an optical imagestabilization circuit according to one embodiment as disclosed herein.

DETAILED DESCRIPTION

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various embodiments of thedisclosure. However, one skilled in the art will understand that thedisclosure may be practiced without these specific details. In someinstances, well-known details associated with optical imagestabilization have not been described to avoid obscuring thedescriptions of the embodiments of the present disclosure.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment. Thus, the appearances of the phrases “in one embodiment” or“in an embodiment” in various places throughout this specification arenot necessarily all referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics may be combined inany suitable manner in one or more embodiments.

In the drawings, identical reference numbers identify similar featuresor elements. The size and relative positions of features in the drawingsare not necessarily drawn to scale.

FIG. 1A is a block diagram illustrating an example of a housing 10according to principles disclosed herein. A camera lens 12, an actuator14, a position sensor 16, and an optical image stabilization circuit 18are positioned within the housing 10. The optical image stabilizationcircuit 18 includes a gyroscope 20, a drive circuit 22, and amicrocontroller 24. In another embodiment, the optical imagestabilization circuit 18 also includes an analog to digital converter tofacilitate communication between the drive circuit 22 and themicrocontroller 24.

The housing 10 may be any device that includes a camera. For example,the housing 10 may be a smartphone, a tablet, a digital camera, or aportable computer with a built-in camera.

The actuator 14 is coupled to the lens 12 and the drive circuit 22. Theactuator 14 is configured to move the lens 12 in response to a powerdrive signal from the drive circuit 22. The actuator 14 may be basedupon a variety of different technologies, such as adaptive liquidlenses, shape memory alloys, or piezo-electric motors. In a preferredembodiment, the actuator 14 is based on a voice coil motor.

The position sensor 16 is coupled to the lens 12 and the drive circuit22. The position sensor 16 is configured to measure a position of thelens 12 and provide position data of the position of the lens 12 to thedrive circuit 22. The position sensor 16 may be any type of sensorconfigured to detect movements of the lens 12. For example, the positionsensor 16 may include photo sensors or hall sensors. In anotherembodiment, the position sensor 16 is coupled to the microcontroller 24and provides position data directly to the microcontroller 24.

The optical image stabilization circuit 18 is coupled to the actuator 14and the position sensor 16. As will be discussed in further detail withrespect to FIGS. 2-3, the optical image stabilization circuit 18performs an image stabilization process to minimize the impact ofmovements or vibrations inflicted upon the housing 10. As previouslystated, the optical image stabilization circuit 18 includes thegyroscope 20, the drive circuit 22, and the microcontroller 24.

The gyroscope 20 is coupled to the microcontroller 24 and the drivecircuit 22. The gyroscope 20 is configured to detect movements of thehousing 10 relative to the object photographed, whose position shouldremain relatively constant. For example, if the housing 10 is asmartphone having the lens 12, the gyroscope 20 detects the movements ofthe smartphone when the user is capturing an image by taking a picture.The gyroscope 20 will sense then output any movement, such as angularrates along lateral, vertical, and longitudinal axes, of the housing 10to the microcontroller 24. In addition, the gyroscope 20 is configuredto output gyroscope data ready signals and gyroscope reset signals tothe drive circuit 22. A gyroscope data ready signal indicates thatmovement data is ready to be processed by the microcontroller 24, and agyroscope reset signal indicates that the gyroscope 20 is in anon-measuring state.

The drive circuit 22 is coupled to the gyroscope 20, the position sensor16, the microcontroller 24, and the actuator 14. As previouslydiscussed, the drive circuit 22 is configured to receive gyroscope dataready and reset signals from the gyroscope 20, and receive position dataof the position of the lens 12 from the position sensor 16. The drivecircuit 22 is also configured to provide a power drive signal to theactuator 14 to move the lens 12. The power drive signal to the actuator14 may include a plurality of transitions from one power level toanother power level. For example, the power drive signal may generate astandard pulse-width modulation. In a preferred embodiment, the drivecircuit 22 provides a multi-state pulse-width modulation signal that canhave any number of different values, duty cycles, and frequencies. Inaddition, the drive circuit 22 is configured to output a control cyclestart signal to the microcontroller 24 to notify the microcontroller 24that a control cycle, as will be discussed with respect to FIGS. 2-3,will begin.

The microcontroller 24 is coupled to the gyroscope 20 and the drivecircuit 22. The microcontroller 24 is configured to receive a controlcycle start signal from the drive circuit 22 and subsequently calculatepower drive signal data to generate power drive signals. Particularly,the microcontroller 24 obtains movement data of the movement of thehousing 10 from the gyroscope 20 and position data of the position ofthe lens 12 from the drive circuit 22. The microcontroller 24 thencalculates power drive signal data based on the movement data and theposition data. The power drive signal data is used to generate powerdrive signals to compensate for any movements and vibrations of thehousing 10. For example, the power drive signal data may provide thefrequency, timing of transitions, and amplitudes of power drive signals.The microcontroller 24 provides the power drive signal data to the drivecircuit 22, which then provides a power drive signal based on the powerdrive signal data to the actuator 14 to move or adjust the lens 12accordingly. The calculation of power drive signal data will bediscussed in further detail with respect to FIGS. 2-3. In anotherembodiment, the position sensor 16 is also coupled to themicrocontroller 24 and provides position data directly to themicrocontroller 24.

It should be noted that although only one drive circuit and one actuatorare shown in FIG. 1A, the housing 10 may include any number of drivecircuits and actuators. In one embodiment, three of each is provided.

FIG. 1B illustrates one physical embodiment of use of the circuit andcompensation as disclosed herein. As shown in FIG. 1B, the lens 12 iswithin a smartphone housing 10. Most smartphones today havesophisticated cameras. In addition, most smartphones today includegyroscopes, accelerometers, and various other sensors to sense movementof the smartphone. Within the housing 10 of the smartphone are containedall of the elements as shown in FIG. 1A, namely, the gyroscope 20, themicrocontroller 24, the drive circuit 22, the lens 12 together withposition sensors and actuators. These are not shown in FIG. 1B becausethey are inside the housing 10. The camera is pointed at a scene 11,which the user is taking a picture of by pressing on button 106. Whenthe user's finger presses button 106 to take a picture, the housing 10moves with a slight wiggle, as indicated by movement lines 103. Thiscauses the camera, as well as the lens, to move. Under normalconditions, the movement of the housing 10, which contains the cameraand the lens 12, occurs simultaneously with taking a picture and willcause the picture to be blurry. However, the picture of scene 11 showsup clear on display 104 because it contains the structure shown in FIG.1A. Namely, when the camera moves while the user is pressing the button106, the gyroscope 20 senses the movement and a power drive signal issent, via the drive circuit 22, to the actuator 14 to move the lens 12opposite to the movement of the housing 10. Since the movement of thelens 12 counteracts the movement of the housing 10, the picture as shownon the display 104 is clear. The operation of the optical imagestabilization circuit 18, the actuator 14, the position sensor 16, andthe lens 12, as further explained elsewhere herein, allows a clear imageof scene 11 to be taken, even though the camera is moving, as shown bythe movement lines 103, at the exact instant the camera is taking apicture.

FIG. 2 is a flow diagram illustrating an example of a process 26 for theoptical image stabilization circuit 18 according to principles disclosedherein. It is beneficial to review the steps of FIG. 2 simultaneouslywith the plurality of wave forms of FIG. 3. FIG. 3 is a diagramillustrating a plurality of wave forms for a plurality of lens movementcontrol cycles N−2, N−1, N, N+1, and N+2 of the optical imagestabilization circuit 18 according to principles disclosed herein. Thewave forms include gyroscope data ready signals 46, gyroscope resetsignals 48, control cycle start signals 50, position measurements 52,calculation of power drive signal calculations 54, and power drivesignals 56, 58, and 60. Each of the wave forms of FIG. 3 will bediscussed in further detail with respect to FIG. 2.

At step 28 of FIG. 2, the process 26 begins. In a subsequent step 30,the drive circuit 22 receives a gyroscope data ready signal from thegyroscope 20. For example, as shown in FIG. 3, the drive circuit 22receives gyroscope data ready signals 46A, 46B, 46C, or 46D from thegyroscope 20. A gyroscope data ready signal indicates that movement datais ready to be processed by the microcontroller 24.

In a preferred embodiment, the frequency of gyroscope data ready signalsis programmable. For example, the gyroscope data ready signals may beprogrammed to have a period of 220 μs, 330 μs, and 440 μs. In theembodiment shown in FIG. 3, gyroscope data ready signals 46 have aprogrammed period of 330 μs.

The drive circuit 22 also receives gyroscope reset signals from thegyroscope 20. The gyroscope reset signals are received throughout theprocess 26. For example, as shown in FIG. 3, the drive circuit 22receives gyroscope reset signals 48 from the gyroscope 20. Eachgyroscope reset signal indicates that the gyroscope is in anon-measuring state for that brief moment in time. Particularly, thegyroscope 20 is not detecting any movements inflicted upon the housing10 during the reset period. The length of a gyroscope reset signal maybe brief, for example, 0.5 μs or 0.05 μs.

In a preferred embodiment, the gyroscope reset signals have a knownfrequency. In the embodiment shown in FIG. 3, the gyroscope resetsignals 48 have a known period of 5 μs. If the reset period is 5 μs, thegyroscope 20, for example, will be sensing data for 4.5 μs, and thenwill stop sensing and be ready to output the data for 0.5 μs at the endof the gyroscope cycle. The gyroscope cycle will then repeat itself. Thegyroscope cycle length and the data sending time can be any selectedamount of time, such as 5 μs with 0.3 μs, 0.5 μs, or 1.0 μs, etc. datasending time. As will be discussed in further detail with respect tostep 42, power drive signals are synchronized with the gyroscope resetsignals. Further, in one embodiment, the frequency of power drivesignals are tracked by counting the gyroscope reset signals.

In step 32, the drive circuit 22 sends a control cycle start signal tothe microcontroller 24. For example, as shown in FIG. 3, the drivecircuit 22 sends control cycle start signals 50A, 50B, 50C, or 50D tothe microcontroller 24. Each control cycle start signal notifies themicrocontroller 24 that a control cycle is ready to begin. For instance,control cycle start signal 50A notifies the microcontroller 24 thatcontrol cycle N−1 will begin, control cycle start signal 50B notifiesthe microcontroller 24 that control cycle N will begin, control cyclestart signal 50C notifies the microcontroller 24 that control cycle N+1will begin, and control cycle start signal 50D notifies themicrocontroller 24 that control cycle N+2 will begin.

After the drive circuit 22 sends a control cycle start signal to themicrocontroller 24, a lens movement control cycle begins in step 34.That is, a control cycle begins in response to the drive circuit 22receiving a gyroscope data ready signal in step 30 and sending a controlcycle start signal to the microcontroller 24 in step 32. For example, inthe embodiment shown in FIG. 3, control cycle N−1 starts subsequent togyroscope data ready signal 46A and control cycle start signal 50A,control cycle N starts subsequent to gyroscope data ready signal 46B andcontrol cycle start signal 50B, control cycle N+1 starts subsequent togyroscope data ready signal 46C and control cycle start signal 50C, andcontrol cycle N+2 starts subsequent to gyroscope data ready signal 46Dand control cycle start signal 50D. Once a control cycle begins in step34, steps 36, 38, and 42 are performed concurrently. As will bediscussed in further detail with respect to step 44, a control cycle mayhave any period length.

In a preferred embodiment, steps 38 and 42 are performed immediatelyupon a control cycle starting in step 34. Namely, the microcontroller 24begins calculating power drive signals in step 38 and the drive circuit22 drives the actuator 14 in step 42. However, step 36 is performedafter a resting period, such as 1-3 μs, to allow any vibrations ortransients of power drive signals from that or a previous control cycleto stabilize. That is, positions measurements in step 36 are started ashort time after a control cycle is started in step 34 to allow noisegenerated by a previous power drive signal to settle. For example, inthe embodiment shown in FIG. 3, power drive signals 56B, 58B, and 60Band calculation 54B are immediately started after the control cyclestart signal 50B, which is subsequent to the gyroscope data ready signal46B. Then, after 1-3 μs, the drive circuit 22 obtains a positionmeasurement during measurement interval 52A of the position measurementsignal 52.

In step 36, the drive circuit 22 obtains position data of the positionof the lens 12 from the position sensor 16. In the embodiment shown inFIG. 3, position measurements are obtained when the position measurementsignal 52 is at a high signal level. For example, position measurementsare obtained from the position sensor 16 during measurement intervals52A and 52B. The position data will be used for a calculation of powerdrive signals in the next control cycle. For instance, referring tocontrol cycle N of FIG. 3, position data obtained during the measurementinterval 52A will be used for calculation 54C during control cycle N+1.

The obtaining of position data is synchronized with power drive signalsto not be during a transition from one power level to another powerlevel. In other words, position data is obtained when power drivesignals are at a constant power level. For example, position data may beobtained prior to or subsequent to a power drive signal transitioningfrom a first power level to a second power level. In the embodimentshown in FIG. 3, the measurement intervals, or high signal levels, ofthe position measurement signal 52 are synchronized to not be during anyof the transitions of power drive signals 56, 58, and 60. By obtainingposition data synchronously with the power drive signals, positionmeasurements will not be adversely affected by any noise generated bythe drive circuit 22. This ensures that accurate position measurementsare obtained.

In a preferred embodiment, as will be discussed in further detail withrespect to step 42, each of the power drive signals is a multi-statepulse-width modulation signal that can have any number of differentvalues, duty cycles, and frequencies. As such, the power drive signalsmay be generated to have known frequencies and to not have transitionsduring certain portions of each period. For example, in the embodimentshown in FIG. 3, power drive signals 56, 58, and 60 are created to haveperiods of 40 μs with no transitions during the first 20 μs of eachperiod. As a result, in step 36, position data may be obtained duringthe first 20 μs of each period. It should be noted that although themeasurement intervals, or high signal levels, of the positionmeasurement signal 52 seems to be shown to overlap the exact start ofeach period of the power drive signals 56, 58, and 60 as it transitionsfrom one cycle to another, position data sensing are a short time after,such as 1-3 μs, the power drive signal starts its cycle so that positiondata is not sensed at the starting transition of a power drive pulse.The position data may be obtained during any portion of power drivesignals in which there are no transitions from one power level toanother power level. For example, the position data can be obtainedduring the second half of each cycle of the drive signal and not duringthe first half.

In step 38, power drive signals for a next control cycle are calculatedby the microcontroller 24 using position data obtained in a priorcontrol cycle. For example, referring to control cycle N of FIG. 3,calculation 54B is performed to determine power drive signals 56C, 58C,and 60C of control cycle N+1, and uses position data obtained in controlcycle N−1. The calculation of power drive signals includes receivingmovement data from the gyroscope 20, receiving position data from aprior control cycle from the drive circuit 22, calculating power drivesignals based on the movement data and the position data to compensatefor any movements of the housing 10, and providing power drive signaldata to the drive circuit 22. For instance, again referring to controlcycle N of FIG. 3, the microcontroller 24 receives movement data fromthe gyroscope 20 during time 62, receives position data obtained incontrol cycle N−1 from the drive circuit 22 during time 64, calculatespower drive signals 56C, 58C, and 60C to compensate for movements of thehousing 10 during time 66, and provides power drive signal data to thedrive circuit 22 during time 68 to be used in the next cycle N+1. Aswill be discussed in further detail with respect to step 42, the powerdrive signal data is then used to generate power drive signals duringcontrol cycle N+1.

In step 40, it is determined whether the calculation of the power drivesignals in step 38 is completed. For instance, referring to controlcycle N of FIG. 3, it is determined whether calculation 54B iscompleted. If the calculation of the power drive signals have notcompleted, the process 26 returns to step 38. If the calculation of thepower drive signals is completed, the process 26 moves to step 44 andwaits until it is the end of the control cycle.

In step 42, the drive circuit 22 drives the actuator 14 for selectedchannels to move or adjust the lens 12. The drive circuit 22 uses thepower drive signals calculated in a prior control cycle. For example,referring to control cycle N of FIG. 3, the drive circuit 22 generatespower drive signal 56B to drive the actuator 14 along an X-axis channel,power drive signal 58B to drive the actuator 14 along a Y-axis channel,and power drive signal 60B to drive an auto focus channel of the lens 12during control cycle N. The power drive signals 56B, 58B, and 60B aregenerated based on power drive signal data calculated during calculationperiod 54A. Based on the power drive signals, the actuator 14 adjuststhe lens 12 accordingly. It should be noted that although only threepower drive signals are shown in FIG. 3, any number of power drivesignals may be generated to adjust the lens 12.

Power drive signals 56, 58, and 60 are examples of any one of differentpower drive signals that can be generated. For example, in oneembodiment, power drive signals are standard pulse-width modulationsignals, each having high (i.e., 1) and low (i.e., 0) voltage levelswith a certain duty cycle or frequency. In a preferred embodiment, powerdrive signals are multi-state pulse-width modulation signals that canhave more than a dozen different voltage levels, duty cycles, andfrequencies. For instance, see U.S. patent application Ser. No.14/976,924, filed on Dec. 21, 2015. In contrast to a standardpulse-width modulation signal in which there are only two voltage levels(high and low), a multi-state pulse-width modulation signal may havevoltage levels of 1, ½, ⅓, ¼, or some other value less than the fullvoltage level and greater than the lowest voltage level and the width ofeach pulse within a cycle can vary greatly.

In a preferred embodiment, power drive signals are synchronized withgyroscope reset signals. Particularly, each power drive signal isgenerated to have any transitions from one power level to another powerlevel to occur concurrently with a gyroscope reset signal. For example,in the embodiment shown in FIG. 3, transition 70 of power drive signal56B is synchronized to be with gyroscope reset signal 72. Bysynchronizing the transitions of the power drive signals with thegyroscope reset signals, the gyroscope signal will be isolated from anynoise generated by the drive circuit 22.

In a preferred embodiment, the frequency of the power drive signals areselected to be above the audio frequency, which is approximately 20 kHz.In the embodiment shown in FIG. 3, the power drive signals 56, 58, and60 have a frequency of 25 kHz or a period of 40 μs.

In one embodiment, the frequency of the power drive signals are trackedby counting the gyroscope reset signals. For example, in the embodimentshown in FIG. 3, the 40 μs periods of the power drive signals 56, 58,and 60 are determined by counting eight of the gyroscope reset signals48, which has a period of 5 μs.

After steps 36, 38, 40, 42 have completed, the process 26 moves to step44. In step 44, it is determined whether it is the end of the lensmovement control cycle that was started in step 34. A control cycle mayhave any period length that begins simultaneous or subsequent to acontrol cycle start signal and ends simultaneous or prior to a nextcontrol cycle start signal.

In a preferred embodiment, a control cycle has a period starting inresponse to a control cycle start signal, such as control cycle startsignal 50B, and ending when in response to a subsequent control cyclestart signal is received, such as control cycle start signal 50C. As aresult, the number of position measurements and length of power drivesignals can be maximized. For example, in the embodiment shown in FIG.3, control cycle N has eight position measurements and eight cycles ofpower drive signals 56B, 58B, and 60B throughout the entire length ofcontrol cycle N. By having numerous position measurements in eachcontrol cycle, calculation of drive signals for the next control cyclemay be based on multiple position measurements. For example, calculation54C of control cycle N+1 may use a median or mean of the eight positionmeasurements obtained during control cycle N. It would also be possible,of course, to have one or two position sensor measurements each controlcycle, but doing so would reduce the quality of the data.

If it is the end of the control cycle, the process 26 returns prior tostep 30. For example, when control cycle N ends, the process returns andmoves to step 30 when gyroscope data ready signal 46C is received.

If it is not the end of the control cycle, the process 26 returns toperform steps 36 and 42. Upon returning to step 36, position data isobtained again when the power drive signals are not transitioning fromone power level to another power level. For example, referring tocontrol cycle N of FIG. 3, position data is obtained from the positionsensor 16 during measurement interval 52B of the position measurementsignal 52. Upon returning to step 42, the drive circuit continues todrive the lens using power drive signals calculated in the prior controlcycle. For example, again referring to control cycle N of FIG. 3, thedrive circuit 22 continues to generate power drive signals 56B, 58B, and60B. As discussed with respect to step 40, after it is determined thatthe calculation of the power drive signals is completed in step 40, theprocess 26 moves to step 44 and waits until it is the end of the controlcycle. Step 38 is not performed again until the next control cycle. Forinstance, once calculation 54B is completed, calculation 54C is notperformed until control cycle N+1 starts.

The optical image stabilization circuit 18 disclosed herein results inreliable and accurate movement data from the gyroscope 20 and positiondata from the position sensor 16.

The various embodiments described above can be combined to providefurther embodiments. All of the U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet areincorporated herein by reference, in their entirety. Aspects of theembodiments can be modified, if necessary to employ concepts of thevarious patents, applications and publications to provide yet furtherembodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

The invention claimed is:
 1. A method of driving a lens for movementrelative to a camera housing in which the lens is located, the methodcomprising: receiving a reset signal from a gyroscope that is positionedwithin the camera housing, the reset signal being active indicating thatthe gyroscope is in a non-measuring state; outputting a power drivesignal at a first power level to drive an actuator that moves the lens;transitioning, concurrently with the reset signal being active, thepower level of the power drive signal from the first power level to asecond power level; outputting the power drive signal at the secondpower level; and obtaining position data of a position of the lens froma position sensor while the power drive signal is at the first powerlevel and prior to the step of transitioning between the first andsecond power levels.
 2. The method according to claim 1, wherein thecamera housing is a smartphone.
 3. The method according to claim 1,further comprising: transitioning the power level of the power drivesignal from the second power level to a third power level; and obtainingadditional position data of a position of the lens from the positionsensor while the power drive signal is at the third power level.
 4. Themethod according to claim 1, further comprising: calculating power drivesignal data of another power drive signal concurrently with theoutputting of the power drive signal at the first power level and theobtaining of the position data.
 5. The method according to claim 1,further comprising: receiving a data ready signal from the gyroscope,the data ready signal indicating that movement data of a movement of thecamera housing is ready for processing, the outputting of the powerdrive signal at the first power level being in response to the dataready signal.
 6. A method of driving a lens for movement relative to acamera housing in which the lens is located, the method comprising:receiving a plurality of reset signals from a gyroscope that is locatedin the same housing as the lens, the plurality of reset signals having afirst frequency, each of the plurality of reset signals indicating thata gyroscope is in a non-measuring state; outputting a power drive signalto drive an actuator that moves the lens, the power of the power drivesignal being constant for a first period time, having a transition fromone power level to another power level within a single cycle of thepower drive signal, and then being constant for a second period of time,the transition being synchronised with a reset signal of the pluralityof reset signals; and obtaining position data of the lens from aposition sensor located adjacent to the lens and in the same housing,the timing of the obtaining of the position data being selected to occurwhile the power of the power drive signal is at a constant power.
 7. Themethod according to claim 6, wherein the camera housing is a smartphone.8. The method according to claim 6, further comprising: counting theplurality of reset signals; and tracking the power drive signal based onthe counting of the plurality of reset signals.
 9. The method accordingto claim 6, wherein the power drive signal has a second frequency thatis greater than 20 kHz.
 10. The method according to claim 6, wherein thepower drive signal has a second frequency that is greater than the firstfrequency.
 11. The method according to claim 6, further comprising:receiving a data ready signal from the gyroscope, the data ready signalindicating that movement data of the camera housing is ready forprocessing, the outputting of the power drive signal and the obtainingof the position data being in response to the data ready signal.
 12. Amethod, comprising: receiving a reset signal from a gyroscope, the resetsignal being active indicating the gyroscope is in a non-measuringstate; outputting a power drive signal to an actuator, the power drivesignal having a transition from one power level to another power level,the transition of the power drive signal being synchronized to beconcurrent with the reset signal being active; and obtaining positiondata from a position sensor, the obtaining of the position data beingsynchronized with the power drive signal to not be during the transitionof the power drive signal.
 13. The method according to claim 12, furthercomprising: receiving a data ready signal from the gyroscope, the dataready signal indicating that movement data is ready, the obtaining ofthe position data being in response to the data ready signal.
 14. Themethod according to claim 12, further comprising: moving a camera lensbased on the power drive signal.
 15. The method according to claim 12,wherein the outputting of the power drive signal and the obtaining ofthe position data are performed concurrently.